Simulating the war in China itself has come with its own challenges. We wanted to make the war feel like the long campaign it was (lasting, historically, from 1937 to 1945), not least because a Japan with a secure China can bring far more resources to bear on other targets than it did historically. At the same time, China starts with crippling penalties to its army, which means that Japan could easily defeat them. This is not particularly historical, as the Japanese expected a quick victory and were rudely surprised as the Chinese divisions fought very tenaciously.
So in order to make the campaign in China feel historical and give the Chinese player a chance to survive the initial invasion, we gave Japan some penalties for fighting in China (or, specifically, when fighting against Chinese troops). These penalties can be reduced through decisions, which raise world tension, so you will have to balance out the need to finish the campaign fast against raising world tension too quickly. We feel that this best represents the disdain the Japanese military held their opponents in - the Chinese simply weren’t worth a proper effort. Of course you, as the player, can hound your military into actually taking this conflict seriously, but the rest of the world may not like the idea of all-out warfare in China.